Safety-stop for elevators.



Patented July 1902'. I

No. 703,548] Y I A. GOWPERTHWAIT. SAFETY STOP FOR ELEVATORS.

2 Sheets-Sheet I.

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- .v A. COWPE'RTHWAIT.

Patented July I, I902.

SAFETY STOP FOB ELEVATORS.

. (Application filed Apr. 16, 1902.)

(No Model.)

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UNiTED STATES PATENT OFFICE.

ALLAN OOWPERTHWAIT, OF BROOKLYN, NEW YORK, ASSIGNORTO WALTER L. TYLER,-OF BROOKLYN, NEW YORK, AND vALONZO 13. SEE, OF NEW YORK, N. Y;

SAFETY-STOP FO-R ELEVATORS.

SPECIFICATION forming part of Letters Patent N0. 703,548, dated July 1,1902. Application filed'April 15, 1902. Serial No. 102,952. (No model.) v

To aZZ whom it may concern:

Be it known that LALLAN COWPERTHWAIT, a citizen of the United States, residing at the city of New York, in the borough of Brooklyn and State of New York, have invented certain new and useful Improvements in Safety- Stops for Elevators, of which the following is a full, clear, and exact description.

This invention relates to safety appliances for elevators, the object being to provide a simple and effective apparatus which will automatically stop the car without serious shock when the speed in lowering exceeds a certain predetermined maximum.

The present invention is a modification of the device shown in United States Patent No. 637,396, issued to Nils O. Lindstrom November 21, 1899. The said patented construction involves a pair of jaws on each side of the car, which are thrown together to clamp the guide-rails by putting tension upon a rope.

which passes around a pair of movable pulleys. The strain of thefrope draws thepulleys together, and they in turn carry wedges between the free ends of the jaws to cause them to clamp the guides. .Thetension on the rope is created automatically by a grip-- ping device, which 'is thrown into action by a centrifugal governor. The rope is normally secured at one end to the upper end of the shaft and passes around the governor carried by the car. When the gripping device, which is also carried by the car, is thrown into action, it necessarily puts a tension on the rope, which tension is utilized in the manner'before described. In the present case the rope instead of running up and down through the shaft is carried by the car, and

The details of the invention will be described with reference to the accompanying drawings, in whichv.

Figure 1 is a vertical section of an elevator shaft and car, showing parts of the mechanism in elevation. Fig. 2 is aplan of the which will hereinafter appear, the depressed portions on one side of the shaft alternating in position with those on the other. side. There are also fixed to the side wall of the shaft in a vertioalrowa numberjof brackets c, from which project two hooks a, each bracket being located a little above one of thedepressions b ofthe cam-track, there being one bracket for each depression. Theelevator-car is indicated by B. Preferably on top of the car and adjacent to each side is mounted in suitable bearings c a shaft e, upon one end of which there is a crank f, carrying a trolley-wheel f, adapted to. run upon the rail 1), to which it is adjacent. At the other end of each shaft is a bell-crank lever, one arm of which, g, is upwardly inclined toward the opposite wall of the shaft and carries a weight g, adjustable in position thereon, and the other arm, 9 being fork-shaped and provided at its outer end with two U- shaped seats 9 opening upward at a position closely adjacent to the side of the shaft, but so related to the other parts that when the trolley f is against the straight portion of the cam-track or in that plane the seats 9 will be in a vertical line above the hooks 0; but when the trolley is in one of the depressions b of the cam-track the said seats g are nearer the middle of the shaft and out of line with the hooks c. To the bottom of the car and on each side are fixed a pair of guide-sheaves t' and t", and along the middle of the bottom of the car are mounted in a suitable framej two sets of pulleys or blocks k and 7;, so mounted in the frame as to be capable of sliding toward and away from each other in the manner fully described in the patent before mentioned. These pulleys are normally separated by the spring 5 between them. Each block is attached to a wedge w, adapted to be moved between the free ends of a pair of jaws 0, pivoted at 0 and having clamping-faces 0 embracing the guide-rails a. It will be seen that when the blocks are drawn toward each other each pair of jaws will be closed upon the respective rails and create a friction, which is utilized herein to stop the car.

a is a rope each end of which carries a crossbar 0". (See Fig. 4.) The cross-bar at one end of the rope normally rests in the seats 9 on one of the bell-crank levers on top of the car. The rope leads thence downward between the side of the car and the shaft over the sheaves i, thence in a loop around the sheaves in the blocks and 7a as many times as there are sheaves in said blocks, thence around the sheave i, thence up the shaft on the opposite side of the car to the second bellcrank at the top, where its cross-bar 1" is seated in the seats g As the car travels up and down the shaft at normal speed or less the trolley-wheels on each side ride along their respective camtracks and into and out of the depressions b as each one is passed. The wheel is caused to enter the depressions by the weight g, the effectiveness of which can be determined by setting the weight at the proper distance from the axis upon which it turns. When the car is traveling downward, the trolley enters a depression just before the seats g reach the level of the hooks or seats 0, and the seats are then moved outward, carrying the cross-bar 7" on the end of the rope clear of the hooks and allowing the car to pass without the rope being caught. \Vhen the downward speed of the car exceeds the predetermined maximum, either by accident or design, the trolley will pass a depression so rapidly that the weight is not given time to force it into the depression. The consequence is that the cross-arm on the rope is not removed out of range of the hooks c and is caught thereon, the seats 9 passing on, relieved of the end of the rope. It will now be seen that one end of the rope is fast to the wall of the shaft, while the other end is fast to the car, it being seated in the other bell-crank. Hence the further movement of the car will put a tension upon the rope and draw the blocks 70 and 7t" together at a speed determined by the number of sheaves in the blocks. This will cause the wedges w to act upon the clamping-jaws and clamp the guide-rails a, creating a gradually-increasingfriction therewitl1,whioheventually stops the car. The graduation of the stop can be predetermined to any extent by the number of sheaves in the blocks and the nature of the frictional surfaces.

Either end of the rope maybe shifted from its seat on the elevator to a seat on the shaft, depending upon which of the bell-cranks acts first. As soon as the cord has been caught on a seat in the shaft the tension at once throws the seat on the opposite bell-crank outward until it is stopped by the crank f striking a lug p on the bearing c. This prevents the apparatus from being thrown out of order by tilting the bell-crank too far and retains the parts in condition to immediately become operative when the car is again started.

Ilaving described my invention, I claim-- 1. A safety device for elevators, consisting of a cord carried by the car, means for automatically engaging said cord with the shaft when the speed of the car becomes abnor mally great, stopping devices for the car and means whereby the tension thus created on the cord by the moving car will operate the stopping devices for the car, substantially as described.

2. A safety appliance for elevators, consisting of a cord carried by the car, devices fixed in the shaft for engaging with the cord, automatic means for causing said engagement when the speed of the car becomes excessive, a gripping device actuated by the cord when itis thus engaged, said gripping device adapted to act upon the guide-rails of the car, for the purpose of stopping the car.

3. In a safety device for elevators, the combination of a pair of clamps adapted to engage with the guide-rails of the car, a pair of movable blocks adapted to actuate said clamps, a cord looped around said blocks and carried by the car, and means for attaching said cord to the side of the elevator-shaft when the speed of the car becomes abnormally high, substantially as described.

4. In a safety device for elevators, the combination of a pair of clamps adapted to engage with the guide-rails of the car, a pair of movable blocks adapted to actuate said clamps, a cord looped around said blocks and carried by the car, said cord being normally fixed'at each end to the car and means whereby one end of the rope will be detached from the car and fixed to the side of the elevator-shaft when the speed of the car becomes abnormally high.

5. In a safety device for elevators, the combination of a car, a cord carried thereby and having its ends normally fixed thereto, stopping devices for the car operated by said cord when put under tension, stationary hooks fixed at intervals in the elevator-shaft, means carried at the extremities of the cord for engaging with said hooks and means whereby the overspeeding of the car will cause said engagement, substantially as described.

(5. The combination of an elevator car and shaft, stoppin g devices for the car, a rope car- In witness whereof I subscribe my signature in presence of two witnesses.

ALLAN OOWPERTHWAIT.

Witnesses:

WALDO M. OHAPIN, FRANK S. OBER. 

